Art of cracking hydrocarbons



Sept. 8,11925.

E. W. ISOM ART OF, CRA-CKING HYDROCARBONS original Filed Nov. 4, 191s 2sheets-snee. 1

INVENTOR Edward WSOWL BY e xMwv- ATTORNEYS Sept. 8, 1925. V 1,553,168

Y E. W. ISOM ART oF CRACKING HYpRocARBoNs original Filed Nov. 4, 1918 2Sheets-Sheet 2 INVENTOR Edward W/am BY gM/z/ @nur MyW ATTORNEY5 Patentedsept. s, v19:25.

UNITED s'rrrglzs PATENT OFFICE.

EDWARD W. ISOM, OF LOCUST VALLEY, NEW YORK, ASSIGNOB TO SINCLAIB REFIN-ING COMPANY, F CH'ICAGO, ILLINOIS, A CORPORATION 0F MAINE. Y

ART or nAcx'ING mnocannons.'

Original application led`November, 4, 1918, Serial No. 261,109.vZDivided and. this application led October 4, 1924.

To all 'whom z'tmay concern.'

Be it known that I, EDWARD W. IsoM, a citizen of the United States,residing at Locust Valley, in the county of Nassau, State of New York,have invented certain new and useful Improvements in the Art of CrackingHydrocarbons; and I do herebye l n 011s, such as heavier petroleum oilsand distillates, for the production of lighter hydrocarbon oilstherefrom by distillation under pressure. More particularly, the presentinvention relates to improvements in the operation of circulatorypressure stills in which circulation iseifected by mechanical forcingmeans such as a pump.

In cracking petroleum oils and distillates by distillation underpressure, temperatures between about 600 and 900 F. and pressures ofasmuch as 100 pounds per square inch or more are commonly employed. For`the most efcient operation of circulatoryr -pressure stills, itisnecessary that the oil be quite rapidly circulated and preferably somemechanical forcing means, such as a pump, is employed to effect rapidcirculation. The use of a mechanical circulating means under theseconditions, however, involves special difficulties.

As thetemperature of the hot circulating oil is far above its ignitiontemperature if exposed to the atmosphere and since the oil is underahigh pressure, one of the problems encountered is the prevention ofleakage of the hot inflammable oil. This problem isl accentuated by thewide-range of tempera-v tures to which the mechanical elements of thePump are subjected. It is also desirable to protect the mechanicalelements of the pump from the hot oil at cracking temperature to asgreat an extent as possible. These Vand other factors which influencethe continuity of operation of the pump are -particularly important withrespect to circulating pumps employed in circulatory cracking systemssince uninterrupted operation of the pump is necessary to protect theheatlng sur- Serial No. 741,580.

i faces of the pressure still during the cracking operation.

' It is one of the objects of the present i11- ventionto provide animproved process of distilling o-ils under mechanical circulation 1semployed and in which the mechanicalcirculating means are operated in animproved manner whereby difficulties such as those referred to above areavoided or minimized. Other and further objects will appear as thedescription proceeds.

According to the present invention, a stuffing box is provided about theshaft or other 'extension operating the mechanical forcing elementswithin the pressure still and relatively cold oil is circulated througha housing arranged externally ofA the'stuing box under a pressuresomewhat in excess of the pressure pervailing'in the still. Escape ,ofthe hot oil at cracking temperature is there by avoided since'anyleakage past the stuffing box will be of cold oil into the still ratherthan of hot oil out. The machanical elements of the circulating meansare also cooled and protected thereby.

The amount of cold oil employed may be just sufficient to prevent theescape of the hot circulating oil, or an additional amount of cold oilmay be employed to secure an increased cooling effect.l Aftercirculation about the stuffing box, the cold oil may be introduced intothe pressure still, or it may be cooled and recirculated. Fresh oil tomaintain the still charge may be employed ressure in which v in thismanner, and may be withdrawn from a supply and introduced wholly intothe still after being used to cool and protect the mechanicalcirculating means, or an additional amount of fresh oil may be employedto obtain anincreased cooling effect and the excess returned to thecommon supply where it is cooled by intermixture with the remainingfresh oil.

In the accompanying drawings I have disclosed .one form of apparatusadapted for practicing the process of the present invention. It 1s tobe`n understood, however, that thisdisclosure 1s for the purpose ofassisting in the comprehenslon ofthe invention, which may be practisedin a great variety of apparatus. The following more' detaileddescription and illustration of one form of the process of the inventionlis for the purpose of exemplication only, and the scope of theinvention is deined in the following claims in which I have endeavoredto distinguish it from the prior art so far as known to me without,however, relinquishing or abandoning any portion or fea- Patent No.1285200 granted to the Sinclair Refining Company November 19, 1918, onmy application.

In the operation of the apparatus` illustrated, the heavy oil to becracked is circulated through a battery of heating tubes located in thefurnace A from the tank C by a forcing device B and thence back to thetank C. Thevapors collecting in the upper part of the tank C may bewithdrawn and condensed'in a condenser 59, diagrammatically illustratedin Fig. 2, andthe pressure in the still may be controlled by regulatingthe valve 60 locatedv in the outlet of the condenser. The oil ismaintained at the appropriate level in the tank C by replenishmg orreplacing the oil driven off in the proceeds.

distillation with fresh oil as the distillation In the apparatusillustrated, the furnace comprises horizontal flues 6 and 7,communicating with fire boxes arrangedupon opposite sides of the flues,and connecting through outlet llues 10 and down-comer ilues 12 to outletiues 13 leading to suitable stacks. The furnace structure may berefractory brick or the like resting, upon a suitable foundation 14 andre-enforced byl buckstaves 15, connected by tie bars 16. The arches 17and 18 and the floors 19 and 20 of the heating ffues are perforatedvertically at. suitable intervals for the passage of batteries ofheating tubes -or pipes 22 which vextend vertically throu h the uesandare connected at top and ottom 'respectively to the manifolds orheaders 23 and 24.- The upper manifold comprises an intermediatemamsupply pipe 25 arranged above the roof of-'the iues and intermediate thelatter, the main pipey "being provided with parallel laterals 26connected to the main pipe by branches 27. Each of the laterals 26'isvfjormed with a series of upwardly and downwardly projecting connectlonbranches ,box 45 about the'shaft. A

28 and 29, there being an upper branch in registry with each lowerbranch. The lower manifold24, except in the respect hereinafterindicated, is similar to the upper manifold 23, and the heating tubes 22extend vvertically between the respective branches on the laterals ofthe upper and lower manifolds and through the roof and Hoor of therespective flues. The upper branches 28 of the upper manifold 23 areclosed by removable hand hole covers 30 and the lower branches 31 oflthe lower manifold 24 are similarly closed. From each end of the main 25return pipes 32 and 33 lead back to the corresponding end of the tank C.From the center of the tank C a main 34 leads downwardly tothe casingy35 of the oil forcing apparatus from which the oil is distributed bybranch pipes 36 and 37 to the opposite ends of the main 38 of the' lowermanifold.

The upper manifold supports the weight of the lower manifold and theheating pipes and is itself supported by I-beams 59 and 60 forming partof the reinforcing structure of the furnace. The tubes 22 are thus freeto expand to the full extent necessary by reason of the great variationin temperature to which the pipes are subjected. The tank C is supportedby stirrups 57 from scaffolding 58.

The oil forcing apparatus illustrated comprises a spiral or screwpropellor arranged in a barrel 40, the shaft 41 of the propellor beingprovided at its outer end with adriving pulley 42 or other means fortransmitting power thereto.l By rotating the propellor in the properdirection, the oil in the still is forced to circulate rapidly from thepump upwardly through the heating tubes to the tank and thence back tothe pump. A

,stuffing box 43 is provided about the shaft 41 and is in turn enclosedin a housing 44 which is likewise provided with a stuing y pump 46,diagrammatically illustrated in Fig. 1, connected to a supply tankcontaining oil of the character being treated is provided forforcing-oil into the, housing 44 through pipe 47 under a pressuresomewhat in excess o-f that within the pump casing 35. A connection 48having a valve 48c therein is provided for introducing oil from thehousing' 44 into the pump casing 35 where it mingles )with the oil beingtreated. A connection 48? yhaving a valve 48h therein leads back tothesupply tank to which the pump 46 is connected. `This tank should be socanstructed and should contain a suliicient supply of oil so thatl thereturn of oil there-to from the housing 44 does not materially heat it.i' g In carrying out the process of the present invention in circulatorypressure stills of the character illustrated, circulation is mainnasalestained by the .'pump B and the escape of hot oil at the crackingtemperature is prevented by circulating relatively .cold oil through thehousing about the stuh'ing box on the pump operating shaft under apressure in excess of that prevailing in the still so that if anyleakage past this stuffing box occurs it is of cold oil into the pumpcasing and not of hot oil/out of the pump casing.

ASuiiicient circulation of cold oilthrough the housing is maintained toprevent its becoming heated to a dangerous temperature so that it isimmaterial if there is leakage past the stufling box 45 on the housing,although by maintaining this stufling box and that part of the shaftpassing through it at a relatively low temperature, it is m'uch easierto maintain a tight 'oint at this point. This circulation Valso coolsand protects all of the pump parts external of the pump casing properand also cools the inner stuing box 43 so that a tighter joint can bemaintained at this point. l

Fresh oil may be supplied to the still in this manner and circulatedthrough the' housing about the stuing'box on the pump casing on itsWayto the still. -All of the oil to maintain the liquid level in thestill Amay be supplied in this manner, vor if lthe 'amount of oilrequired to maintain the still chargeis insuliicie'nt to providethe-desired cooling of the housing, additional oil may be circulatedthrough the housing and thence back to the supply tank- -through'connection 48?. r1 he valves 48h and 48c are cmplo ed to controlthe`amount of oil recirculate to the supply tank through connection 48aand introduced into the cracking system through connection 48,respectively. v

It will thus be seen that the present in-.

vention provides an improved method of operation of circulatory.pressure stills in which circulation is effected by means of amechanical forcin means, such 'as a pump whereby leakage o hot oil isavoided an the mechanical elements of .the forcing lmeans are cooled andprotected'in an impoved manner. lIn another aspect, itl will apparentthat this invention provides #a novelA and advantageous methodofintroducing-'fresh 'oil into 'circulatoig cracking stills wherebytherelatively col freshoil is utilized to preventleakage and to cool andprotect the mechanical circulating means.

This application is a division of my prior i application liled November'4, 1918, Serial Number 261,109.

I claim:

1. A method of cracking oil in circulator j pressure stills, whichcomprises mechanica ly circulating theoilrom and't'o-a bulk supply tankthrough. a heater, heating the oil tov a vcracking temperature in theheater,

i introducing fresh oil into the circulating oil during the progress ofthe distillation'and nally `tive y Ipressuieiil excess of thatprevailing inthe employing the fresh oil for cooling the mechanicalcirculating means before introducing it intofthe'still.

2. A `method of operating circulatory pressure cracking sills in whichoil is circulated from and to a bulk supply tank through a heater inwhich it is heated to the cracking temperature, which comprisesmechanically circulating the yoil by means operated by an extensionextending through a stufng box and a housing arranged externally of thestuffing box, circulating relatively cold oil through the housing undera pressure in excess yof that -prevailing in the still ,and introducingoil from the' housing into the circulating oil in the still.

3. A method of operating circulatory pressure cracking stills in whichoil is circulated from and to a bulk -supplytank through a heater inwhich it is heated to the cracking temperature, which comprisesmechanically circulating` the oil by means operated by an extensionextending through a stuiin bex and 'a housing-arranged extercold oilthrough the housing under a still and introducing part of the oilcirculated through the housing into the oil `in the still.

5. A method of cracking oil in circulatory pressure sti1ls,whichcomprises mechanically circulating the, oil from and to a bulk supplyytank through a heater, heating the oil yto a crackin temperature in theheater, einployingres oill for cooling the. mechanical circulating meansand introducing part of theifresh oil employed for cooling into thecirculating oil in the still.

e. A method-,of .tracking @i1 in circulatory )ressure stills,wl iichcomprises mechanically circulating the' oil from and to a bulk supplytank-through a heater, heating the oil t'o"a crackingtemperature inthe'heater, in-

traducing fresh .oil into the mechanicalcirculating means so thaatt itfirst contacts with the hot oil in the still" therein and employingthefresh oil for coolingthe mechanical circulatingmeans beforeintroducing it into the lerated by-an extension extending through o thestuffing box, circulating relai '7; A method of tracking `Oil incirculatory` 1 30 pressure stills, which comprises circulating stuinghox, circulating fresh oil through the oil from and to a bulk supplytank the housing under a pressure in excess of through aheater, heatingthe oil to a erackthat prevailing in the still and introducing 10 n ingtemperature in the heater, mechanically fresh oil from the housingintothe circulatcirculating the oil by means operated hy an ing hot oil inthe still.

extension extending through a stuffing box ln testimony WhereofI aix mysignature.

and a housing arranged externally ofthe EDWARD' W. ISOM.

